FIG. 1, relative to the prior art, diagrammatically shows an embodiment of this method. The nozzle (100) for spraying/fusion of the powder consists in 3 concentric cones delimiting between their walls tapered annular spaces that are also concentric. A laser (150) passes through the inner cone (130) through a bore centred on the axis of said cone. The laser is focused on the point (191) where the material deposition (192) is carried out on the item (190) being manufactured. Powder (160) is sprayed in the tapered annular space between the inner surface of the outer cone (110) and the outer surface of an intermediate cone (120), while a gas is blown into the tapered annular space between the inner surface of said intermediate cone (120) and the outer surface of the inner cone (130). The centring of the cones (110, 120, 130) in relation to one another and the adjusting of the parameters result in that the powder is sprayed according to a hollow conical stream the apex of which is, ideally, confounded with the focal point (191) of the laser (150). The distance (193) between the point (191) of material deposition and the front end of the outer cone (110) is commonly about 5 mm. This small distance, increases the risks of collision between the cone and the item or the elements of the manufacturing environment such as the table of the machine or means of clamping, particularly when the operation of additive manufacturing is carried out according to trajectories that implement 5 axes of displacement. In certain circumstances also, built-up heaps of powder are created at the outlet of the annular space between the outer cone (110) and the intermediate cone (120, modifying the shape of the stream of powder, leading to degraded deposition conditions. These conditions require the replacement the outer cone (110).
These repair operations according to prior art are expensive as they require the replacement of the entire outer cone, a precision part, which itself is often made from an expensive material such as copper, although only the end of this part is degraded. In addition, the operation is relatively long, leading to the immobilisation of the machine and the occupation of a qualified technician throughout the entire duration thereof.